Ireland suffer O'Brien KO
Munster's Peter O'Mahony will start at the Aviva Stadium
Last Updated: 08/03/12 5:16pm
Sean O'Brien: Has a foot problem
Ireland have been forced into a reshuffle with flanker Sean O'Brien ruled out of Saturday's RBS Six Nations clash against Scotland with a foot problem.
Munster's Peter O'Mahony will replace the reigning European player of the year with Shane Jennings drafted onto the bench.
"Sean has a skin infection on his foot which has failed to recover as quickly as expected," read an Irish Rugby Football Union statement.
The attrition rate from Ireland's 17-17 draw with France on Sunday has been high with O'Brien the third player to be made unavailable for Scotland.
On Monday captain Paul O'Connell and scrum-half Conor Murray were ruled out of the remainder of the Six Nations because of knee injuries.
Ireland's schedule of four games in four weeks - a product of the weather-enforced postponement of their match against France - is stretching their playing resources.
O'Mahony is highly-rated and is a more natural openside than O'Brien, but the 22-year-old has only won two caps as a replacement against Italy and France in this championship.
The more experienced O'Brien came to the fore last season when his explosive ball-carrying made him a central figure for Ireland and Leinster.
The 25-year-old was switched from blindside to openside flanker during the World Cup and continued to bulldoze a path through opposition defences.
While he has not had the same impact in this Six Nations, he is remains a key component of Ireland's vaunted back row.
Ireland team manager Mick Kearney revealed that O'Brien is expected to return against England in the final game of the championship on Saturday week.
"We knew Sean was carrying this infection in his foot, but unfortunately it has not cleared as quickly as we expected," Kearney said.
"While it has not healed enough for him to play this Saturday, we expect him to be fine for next weekend."